Pop/Thud coming from RR!! 2014 DCLB 4x4??

Put a 1.5" leveling kit all the way around. Have checked u-bolts and re-torqued. Still getting the pop when hitting a bump at 45 mph. Input would be helpful! Thanks

 

Did you use blocks or add a leaf for the rear. I'm not to sure if this is the same but we installed some blocks on my friends chevy and each block was angled on one side so the axle can be tilted up or down. Also check your u joints

 

I used to get a pop when I would go up a driveway that was higher than the street; when the rear would flex. It stopped when I changed my leafs.

 

I used blocks that are tapered like you said. Installed them to rotate the pinion up. So it would keep the drive shaft at the proper angle.

 

Wondering if the flip kit will eliminate the popping?